Guide

Fraud Prevention & Caller Identity

Telecom intelligence is a primary weapon against digital fraud. Learn how to detect VoIP and disposable numbers, prevent toll fraud, and ensure your outbound calls get answered.

VoIP & Disposable Number Detection

Fraud syndicates rely on Non-Fixed VoIP and disposable virtual numbers. These can be generated programmatically in thousands of concurrent instances via cloud platforms. Because they aren't tied to a physical address, SIM card, or KYC checks, they provide anonymity for:

  • SMS spam campaigns
  • Fake social media account creation at scale
  • Credential stuffing attacks

Enterprise security must integrate Phone ID and Line Type Intelligence APIs into user registration flows. When a user submits a number, the backend queries the API. If it returns Non-Fixed VoIP, disposable, or special-rate, the system executes defensive logic.

Caveat: Blocking ALL VoIP outright can penalize legitimate enterprise users with corporate cloud telephony. Best practice: restrict VoIP from creating accounts OR require additional multi-factor authentication.

Line type can also change after assignment: a number originally issued as mobile or landline may since have been ported to a VoIP operator. Veriphone's Current lookup (mode=current) returns current_line_type, exposing numbers now served as VoIP even when the original line type looks safe.

Some CPaaS APIs (like Twilio Lookup v2 and Vonage Identity Insights) additionally generate risk scores combining line type with behavioral metadata.

International Revenue Share Fraud (IRSF)

Also called Toll Fraud, IRSF is one of the most costly attack vectors in telecommunications. Here's how it works:

  1. 1 Attackers compromise corporate PBX systems or exploit web app callback functions
  2. 2 The compromised systems automatically dial special-rate international numbers owned by the attackers
  3. 3 The corporate victim gets billed exorbitant connection fees
  4. 4 Attackers siphon revenue share from the special-rate termination point

Defense

Block special-rate numbers in outbound routing using Line Type Intelligence. Integrate number classification into your call routing logic so that any attempt to dial a special-rate or high-risk international destination is flagged and blocked before connection.

Caller ID, CNAM, and Branded Calling

While validation ensures you can reach a user, the inverse — ensuring users recognize and answer your calls — relies on Caller ID technology.

How CNAM Works

When an enterprise places a call, two data pieces are sent: the numeric Caller ID (CLID) and the alphanumeric Caller Name (CNAM). Unlike CLID which travels with call data, CNAM uses a decentralized receiver-pull architecture — the terminating carrier performs a database lookup against a Line Information Database (LIDB).

CNAM Limitations

  • No single centralized global CNAM database
  • Outdated databases show wrong names or "Unknown"
  • Local device contacts override network CNAM
  • Many US mobile carriers treat CNAM as a paid opt-in feature

Branded Calling — The Modern Solution

Branded Calling uses IP networks and STIR/SHAKEN cryptographic frameworks to bypass LIDB lookups entirely. It injects verified brand names, logos, and call reasons ("Fraud Alert", "Delivery Update") onto the recipient's screen. This restores trust, fights robocall spoofing, and significantly increases answer rates.

Key Takeaway

Integrate Line Type Intelligence into every registration flow to block disposable numbers and prevent IRSF. For outbound communications, invest in Branded Calling with STIR/SHAKEN authentication — legacy CNAM is unreliable. The cost of fraud prevention is a fraction of the losses from undetected abuse.

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